Method of measuring the rate of flow of liquid



Dec. 21 ,192e. 1,611,502

C. M. ALLEN METHOD OF MEASURING THE RATE OF FLOW 0F LIQUID.

Original Filed Oct. 2, 1922 0 L (Q g,

,158'! evz B 62% Patented Dec. 21, 1926. l

warren srres) Persia onannns 1r. ALLEN, or Wonons'rnn, massaonusnrrs.

METHOD- OF MEASURING RATE OF FLOW F LIQ'UH).

Original application filed October 2, 1922, Seiial 116.591.997, and incanada July 7, 19

this application filed June 3, 1926. Serial No. 113,582. 7

This is a division of my copending application Serial No. 591,997, filedOct. 2, 1922. This invention relates to a method of measuring the timewhich a liquid takes in passing from one point to another through apipe, penstock, or the like. of constant or varying cross sections sothat the rate of flow can be determined. The principal object of theinvention is'to 10 provide a method of measurement which can be useduniversally even where the Water cannot be seen and which will beaccurate, reliable, and simple.

Reference is'to be had to the accompanying drawingwhich is adiagrammaticview of a penstock showing how thismethod can be carried out inconnection therewith.

This method depends upon the fact that the electrical conductivity of aliquid no changed by certain chemicals which may be held in solutiontherein. It consists briefly in introducing into the pipe or otherconductor a salt or other soluble compound which'will affect theelectrical conductivity of the liquid and observing the time of. in-

troduction of i the compound, and, at the point belowythe time ofinitial appearance,

maximum density and final disappearance thereof. One way to do this isto measure the current that passes between two electrodes introducedinto the pipe, or to measure the voltage or resistance. r

' In the form shown, the flow of wateris being measured in a large steelpenstock 13 as or conduit of constant or variable section.

At the upper end of the penstoclr, which can be taken as a startingpointin some cases,

a quick acting'valve l0 is located in it. This is shown as placed at thecenter otthe pen to stock 13 at its end and'in the plane of theentrance. The solution is piped to thisvalvc from a tank 15 elevated toive any desired head or a pressure tank can 'e used. In the tank isplaced a solution of-a soluble salt or com ound which will afiect theconductivity of t e water as for example common-salt. The quick actingvalve can be operated by a handle 16 and preferably is arranged so thatit may At a distance downstream 10 is placed a pair of electrodes 20.The volume of water in the conduit between the point of introduction andthe electrodes is E known: One of these electrodes is connected be heldopen for any desired. length m of time. 1

from the valve"- 25. Divided and with one side of the line 19. The otheris connected through a switch 21 with an electrical measuring instrument22, as for example an ammeter which is connected to the other side ofthe line. This ammeter should .60 be of a type in which the oscillationsare well damped and may conveniently be controlled. The amineter usuallyshows an initial reading depending upon the acidity of the water and thesize and distance apart as of the electrodes.

Tel'cphonic or other instantaneous C0111- munication' is establishedbetween two observers, one at the point at'which the salt solution isintroduced, that is, 'at the valve 10, to and the other at the ammeter.Stop watches can be employed to determine the time of the firstappearance of a change in the electrical conductivity of the water, timeof maximum. density and time of disappearance. The "35 center of gravitof the change can be determined from t 'ese factors. This is an exampleof one way to-carry out the method. The voltage or resistance can bemeasured instead of the current or the observations can be made in anyscientific way, for example by-recording instruments. In 0 oration, thesoluble compound, as for cramp e, salt, insulation in the tank, isintroduced-into the penstock or conduit 13 by 4 opening the valve 101.At the instant this valveis opened and closed, signals by telephone orotherwise are given to the observer at the ammeter and the stop watchesare started. He observes the amineter and notes as the time of initialappearance of increased conductivity that results in a larger current,also the time of maximum density of con-i ductivity and, if desired,disappearance of the increased current.

ll find in practice that the time of initial appearance of increasedcurrent and the time of maximum current are definite and reliable 1 butthat the time of disappearance of the change is indeterminate andtherefore the 1 0 mean'time'which involves that is unreliable.

'Comparison bf tests made in this way with "thoseconducted with a weir,weighing tank,

or standard measuring. device, shows rthat 1 the elapsed time betweenintroduction and mam'mum density of solution can he accuratelydetermined. The; time elapsed a s stated above' appears to give thecorrect time independent of the length or variation in diameter andinternal condition of the pipe 119 but more accurate results areobtained by observing the time of passage of the center ofgravity of thecharge. Having determined the elapsed time by this method the rate offlpw is found by the well known formularate cu. ft. per S9c.:Volume incu.- ft. divided by time in seconds. Reasonable variations in thestrength of charge of the solution, the length of charge, the amount ofdeflection of the instrument, size and clearance of the electrodes donot affect materially the accuracy of the results. I have also comparedthe results of this method with the so-called color method in which asoluble color is used to measure the rate of flow and which is limitedto cases in which the water can be seen'and I find that the accuracy ofthe present method is greater than that of the color method.

Although I have illustrated and described. only a single apparatus andreferred to only a single soluble compound for use in connection withthis method, I am aware of the fact that the invention is capable ofbeing carried out independent of the particular apparatus illustrated,and that it can be performed accurately with any soluble comclaim ispound that afiects the electrical conductivity of the liquid inaccordance with the claims. -Having described my invention, what I 1.The method of measuring the rate of flow of water in a conduit, whichmethod consists in introducin into the water flowing freely in-Vtheconduit a doluble substance aeintoa which locally alters the electricalconductivity of the water; measuring the resulting changes produced bythe solution in an electric current passing between two electrodesimmersed in the water and constituting parts of an energized circuit,the location of which pair of electrodes-with reference to the point ofintroduction being such as to include between the two points a knownvolume of water, and measuring the elapsed time be tween the time ofintroduction and the time of any change in the electric current betweenthe pair of electrodes.

2. In an apparatus for measuring the rate of flow of water in a conduit,the combination with the conduit for the Water, of a supply tank for asoluble substance that will alter the electrical conductivity of thewater, a pipe leading from the supply tank to said conduit forconducting said soluble substance into the conduit and constituting thepoint of introduction, a valve in said pipe, means whereby the yalve canbe actuated quickly to-introducc small quantities of the solublesubstance into the conduit, a pair of electrodes in the conduit at adistance below the point of introduction such that the volume of waterbetween the point of introduction and the electrodes can be determined,and an electric circuit including said electrodes and an electricalmeasuring instrument.

In testimony whereof I have hereunto atfixed my signature.

CHARLES M. ALLEN.

